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The invention relates to a rotor (10) of a dual centrifuge, said rotor
having a rotor head (12) and an additional rotational mechanism for at
least one rotational unit (22) which is provided in the rotor head (12)
and comprises a bearing (70) and a rotational head (24) that is connected
to the bearing (70), is rotatably mounted therein and can be driven
relative to the rotor head (12) by means of the additional rotational
mechanism, an opening (16) for the rotational unit (22) being provided in
which the rotational unit is accommodated and by means of which the
bearing (70) is arranged such that it is fixed relative to the rotor head
(12). The invention is characterized in that the rotational unit (22) has
a housing (26) in which the bearing (70) is accommodated and in which the
rotational head (24) engages, and in that the housing (26) and the
rotational head (24) form, with bearing (70), a structural unit, the
housing (26) being mounted such that it cannot rotate relative to the
rotor head (12) and such that it can be detached from the rotor head.

1. Rotor (10) of a dual centrifuge, said rotor having a rotor head (12)
and an additional rotational mechanism for at least one rotational unit
(22) which is provided in the rotor head (12) and comprises a bearing
(70) and a rotational head (24) that is connected to the bearing (70), is
rotatably mounted therein and can be driven relative to the rotor head
(12) by means of the additional rotational mechanism, wherein a recess
(16) for the rotational unit (22) is provided in which the rotational
unit is accommodated and by means of which the bearing (70) is arranged
such that it is fixed relative to the rotor head (12), characterized in
that the rotational unit (22) has a housing (26) in which the bearing
(70) is accommodated and in which the rotational head (24) engages, and
in that the housing (26) and the rotational head (24) form, with bearing
(70), a structural unit, the housing (26) being mounted such that it
cannot rotate relative to the rotor head (12) and such that it can be
detached from the rotor head.

2-15. (canceled)

16. Rotor (10) of a dual centrifuge, comprising: said rotor having a
rotor head (12); said rotor has an additional rotational mechanism for a
rotational unit (22); said rotational unit (22) is provided in said rotor
head (12); said rotational unit (22) comprises a housing (26), a bearing
(70) and a rotational head (24) which together form a structural unit;
said rotational head (24) is connected to said bearing (70); said housing
(26) is connected to said bearing (70); said bearing (70) enabling
rotation of said rotational head (24) relative to said housing (26); said
rotational head (24) is driven relative to said rotor head (12) by means
of said additional rotational mechanism; a recess (16) in said rotor head
(12); said rotational unit (22) partially resides in said recess (16) of
said rotor head (12); said housing (26) of said rotational unit (22) is
fixed to said rotor head (12); and, said housing (26) cannot rotate
relative to said rotor head (12) and is detachable from said rotor head.

17. Rotor according to claim 16, further comprising: said recess (16)
extends through a portion of said rotor head (12); said rotational unit
(22) is mounted therein and extends through said recess (16); and, a
lower portion of said housing (26) of said rotational unit (22) protrudes
from said recess (16) and is exposed.

18. Rotor according to claim 17, further comprising: said rotor head
includes has a rotationally symmetrical basic shape defining an envelope;
said housing includes a lower region protruding beyond said envelope.

19. Rotor according to claim 18, further comprising: said housing (26)
has a height and at least 30% of said height of said housing (26)
protrudes beyond said envelope.

20. Rotor according to claim 17, further comprising: said lower region of
said housing (26) has cooling ribs (42).

21. Rotor according to claim 17, further comprising: said rotational unit
(22) is securely connected to said rotor head (12) by means of a
releasable quick fastener or a screw connection.

22. Rotor according to claim 17, further comprising: said housing (26)
has sides, and on a side of said housing (26) which is remote from said
cooling fins (42), a flange (84) is provided which bears against said
rotor head (12).

23. Rotor according to claim 17, further comprising: said recess (16) and
said housing (26) are adapted to each other.

24. Rotor according to claim 23, further comprising: said housing (26)
includes a cross-sectional shape and said recess (16) includes a
cross-sectional shape; said cross-sectional shape of said housing (26)
and said cross-sectional shape of said recess (16) form an anti-rotation
means in a polygonal shape or a cylindrical shape with projections and
associated grooves.

25. Rotor according to claim 17, further comprising: said housing (26)
and a housing cover (80) with a central bore for a drive shaft (25) of
said rotational head (24) delimit a bearing space (64) with bearings (70)
for a drive shaft (25).

26. Rotor according to claim 25, further comprising: said bearing space
(64) is encapsulated toward the outside in a lubricant-tight manner.

27. Rotor according to claim 25, further comprising: said bearing space
(64) is filled with lubricant; and, said lubricant is roller-bearing
grease SKF LGBB2/0.4.

28. Rotor according to claim 26, further comprising: said bearing space
(64) is filled with lubricant up to 50% of said height of said bearing
space (64).

29. Rotor according to claim 17, further comprising: said rotational unit
(22) has a surface; and, as large as possible portion of said surface of
said rotational unit (22) is in contact with said rotor head (12) for
heat dissipation.

30. Rotational unit (22) for a rotor, comprising: a housing (26), a
bearing (70) and a rotational head (24) which together form a structural
unit; said structural unit includes mounting means for affixation to said
rotor; and, said structural unit includes driving means for being driven
by said rotor.

Description

[0001] This patent application is the national phase entry of
PCT/EP2015/077534, international application filing date Nov. 24, 2015,
which claims the benefit and priority of and to German patent application
no. 10 2015 100 006. 7, filed Jan. 2, 2015.

[0004] Dual centrifuges have already been known for several years. While
in a conventional centrifuge samples are rotated about a single axis, in
a dual centrifuge samples are rotated about a main axis and at the same
time about a secondary axis. Due to the resulting high centripetal force
and the centrifugal forces acting in different planes, a higher
efficiency is achieved during centrifugation, especially during mixing,
when separating or during homogenization of the samples.

[0005] DE 10 2012 105 819 A1 discloses a device for the homogenization and
separation of samples which comprises a centrifuge having a rotor body.
Rotational units are mounted in blind-hole type recesses in the rotor
body and arranged so that they can be rotated about a secondary axis of
rotation which differs from the axis of rotation of the motor (main axis
of rotation). A separate drive is provided for the rotational units so
that the rotary movement of the rotational units is generated independent
of the drive of the rotor body.

[0006] The above invention is an improvement over the prior art in
particular in that lubricant escaping from a bearing of a rotational unit
remains in the recess associated with the rotational unit where it
continues to be available in the area of the bearing. Significantly
longer operating times can therefore be achieved than with prior art
solutions.

[0007] However, practice has shown that during long-term operation,
problems due to insufficient cooling will arise in devices according to
this invention since the heat created during rotation of the rotational
unit accumulates in the recess and cannot be dissipated. Furthermore,
there is room for improvement regarding maintenance, repair and cleaning
of the device. Especially parts of the bearing that are integrated in the
rotor body, such as a bearing outer ring, are difficult to access due to
the very small dimensions of the recesses.

[0008] It is the object of the invention to avoid the above mentioned
shortcomings and to provide a rotor for a dual centrifuge which can be
serviced more easily and thus reduces downtime. In particular, the
rotational units and recesses associated with the rotational units should
be easily accessible for the purpose of maintenance, repair and cleaning,
and sufficient cooling for long-term operation should be provided.

[0009] The invention is based on the finding that decoupling the bearing
of the rotational unit from the rotor body creates better conditions for
maintenance, repair and cleaning, as well as for cooling the rotational
unit. In addition, this opens up additional design options for optimizing
maintenance and cooling.

[0010] According to the invention, the rotor of a centrifuge has a rotor
head and an additional rotation mechanism for at least one rotational
unit disposed in the rotor head. The rotational unit includes a bearing
and a rotational head connected to the bearing and rotatably mounted
therein, which can be driven relative to the rotor head by means of
another rotation mechanism. Here, a recess for the rotational unit and/or
for each rotational unit is provided in which it is introduced, thus
securely mounting the bearing relative to the rotor head. According to
the invention, the rotational unit has a housing which accommodates the
bearing and which is engaged by the rotational head, and the housing and
the rotational head with the bearing form a structural unit, with the
housing being mounted in the rotor head such that it cannot rotate
relative to the rotor head and such that it can be detached from the
rotor head. This clearly facilitates operation and prolongs the service
life of the centrifuge because detachably mounting the housing in the
rotor head considerably facilitates cleaning, maintenance and repair of
the bearing of the rotational unit. The rotational unit can be removed
easily from the rotor head and maintained independently of the rotor
head. In addition, the rotational unit can be easily replaced which
reduces maintenance-related downtime to a minimum.

[0011] According to one aspect of the invention, the recesses extend
through a portion of the rotor head. When mounted, the rotational unit
passes through the recess, and a lower portion of the housing of the
rotational unit protrudes from the recess and is thus exposed to the
environment. This arrangement avoids heat accumulation in the recess and
the exposed portion is cooled by air flowing past during rotation.

[0012] Moreover, owing to the presence of the recess, the length of the
rotational unit is not restricted by the dimensions of the rotor body.
With the dimensions of the rotor body unchanged, this allows the use of
longer rotational units which may, for example, accommodate larger
bearings for larger sample vessels. This saves space as well as costs.

[0013] In a further advantageous embodiment, the rotor head has a
rotationally symmetrical basic shape with an outer surface, with the
lower region of the housing protruding beyond this outer surface. This
configuration improves the cooling effect, since the protruding portion
of the housing provides a good contact surface for the air flowing past.

[0014] It has proven particularly efficient to have at least 30%,
preferably at least 50%, of the height of the housing protrude from and
above the outer surface, since this will yield an optimum ratio of the
cooling effect of the air flowing past and the mechanical stress/safety.

[0015] Cooling can be further improved by providing cooling ribs in the
lower region of the housing so as to enlarge the cooling surface of the
rotational unit.

[0016] The cooling ribs can be aligned and bent in the direction of
rotation of the rotor head, and have a radius starting from the
rotational axis of the rotor head that is sufficient to achieve an
approximately laminar air flow and to largely prevent no-flow zones and
thus non-uniform cooling of the housing. However, various experiments
have shown that a turbulent air flow will yield even more efficient
cooling. Therefore, it is advantageous if the cooling ribs are positioned
at an angle relative to the direction of rotation.

[0017] According to a further aspect of the invention, the rotational unit
is firmly connected to the rotor head by means of a releasable quick
fastener or screw connection. This facilitates mounting and maintenance
of the rotational unit.

[0018] In a preferred embodiment, on the side of the housing remote from
the cooling ribs, a flange is provided which abuts against the rotor
head. This flange acts to secure the housing in its associated recess in
the direction of the longitudinal axis of the housing.

[0019] In one advantageous embodiment of the invention, the recess and the
housing of the rotational unit are matched to each other. This allows the
housing to be secured in other directions as well, besides the direction
of its longitudinal axis, which increases the safety of the centrifuge
and prolongs the service life of the rotational units.

[0020] This securing can be further improved by anti-rotation means formed
by the cross-sectional shape of the housing and the cross-sectional shape
of the recess, in particular a polygonal shape or a cylindrical shape
with projections and associated grooves. In addition to securely mounting
the housing relative to the rotor head as described above, this also
avoids undesired rotation of the housing about its own axis.

[0021] According to another aspect of the invention, the housing and a
housing closure with a central bore for an axis of rotation of the
rotational head delimit a bearing space with bearings of the rotational
axis. Such a closed bearing space has the advantage that in the event of
glass breakage of sample containers, possible contaminants can be
contained better.

[0022] Preferably, the bearing space is encapsulated towards the outside
in a lubricant-tight manner. Consequently, any lubricant escaping from a
bearing will be contained within said housing for the entire
centrifugation period and will thus be available in the area of the
bearing. This significantly reduces the risk of the bearing seizing up.
Furthermore, this prevents contamination of the rotor head with
lubricant.

[0023] It is advantageous if the bearing space is filled with lubricant,
especially grease, preferably roller bearing grease SKF LGBB2/0.4. As a
result, the bearing will be lubricated during the entire operating time,
thereby virtually eliminating bearing seizure.

[0024] In a preferred embodiment of the invention, the bearing space is
filled with lubricant to up to 50% of the height of the bearing space.
This prevents excess lubrication of the bearing.

[0025] To be able to check bearing lubrication at any time and to
replenish lubricant, if necessary, a lubricant level indicator and/or a
lubricant refill valve may be provided.

[0026] In an advantageous further development of the invention, an as
large as possible part of the surface of the rotational unit is in
contact with the rotor head. This ensures optimal heat dissipation from
the rotational unit into the rotor head.

[0027] The invention also relates to a rotational unit for a rotor having
the above mentioned features.

[0028] Additional advantages, features and possible applications of the
present invention will become apparent from the following description in
which reference is made to the embodiments illustrated in the drawings.

[0029] Throughout the description, the claims and the drawings, those
terms and associated reference signs are used as are listed in the List
of Reference Signs which follows below. In the drawings:

[0030] FIG. 1a is a perspective view of a rotor 10 according to the
invention with two rotational units 22;

[0031] FIG. 1b is a sectional view of the rotor 10 of FIG. 1a;

[0032] FIG. 2 is a perspective view of an inventive embodiment of a
rotational head 24 without the gearing 36;

[0033] FIG. 3 is a perspective view of an adapter 50 according to the
invention;

[0034] FIG. 4 is an exploded view of a rotational unit 22 of the
invention;

[0035] FIG. 5a is a view of the rotational unit 22 of in FIG. 4; and

[0036] FIG. 5b is a view of a lateral section of the rotational unit 22
shown in FIG. 4 and FIG. 5a taken along the cutting line and in the
cutting direction C-C depicted in FIG. 5a.

[0037] FIG. 1a is a perspective view of a rotor 10 according to the
invention with two rotational units 22 for use in a dual centrifuge not
shown in the figures. FIG. 1b is a sectional view of the rotor 10
illustrated in FIG. 1a.

[0038] The rotor 10 has a rotor head 12 of a rotationally symmetrical
basic shape, which defines an envelope. The rotor head 12 is provided
with a bottom 15 and a circumferential wall 14 which surrounds the bottom
15 and extends upwardly. A drive axis A runs perpendicularly through the
center 13 of the rotor head 12. A drive shaft not shown in the figures
extends with its free end through a recess 18 which is provided in the
bottom 15 and concentric with the drive axis A. Above the recess 18, a
receiving tube 20 is disposed which is integrally formed with the bottom
15 and which serves to center and vertically secure the rotor head 12 on
the drive shaft.

[0039] The wall 14 has a vertical portion 14a and an oblique portion 14b
which inclines downward toward the drive shaft. Two recesses 16 are
provided which are located opposite each other relative to the drive axis
A and which partially extend through the vertical portion 14a of the wall
14 and the oblique portion 14b of the wall 14. The rotational units 22
are accommodated in the respective recesses 16.

[0040] The rotational units 22 each have an axis of rotation R1, R2 and
are aligned by the recesses 16 in such a way that the rotational axes R1
and R2 intersect the drive axis A at an acute angle above the rotor 10.
Furthermore, the free ends of the rotational units 22 facing away from
the drive axis A, i.e. the housings 26 described below, protrude from the
envelope in the area of the oblique portion 14b of the wall 14.

[0041] Each rotational unit 22 has a largely rotationally symmetrical
outer contour, and comprises a rotatably mounted rotational head 24 (see
FIG. 2) for supporting an adapter 50 for material to be centrifuged (see
FIG. 3), and a housing 26 (see FIG. 4) in which a bearing 70 for the
rotational head 24 is provided, which is in turn engaged by the
rotational head 24 with a bearing shaft 25 that is provided on its side
facing the housing 26. Part of the bearing shaft 25 is visible in FIG. 2
and in FIG. 5b.

[0042] The rotational head 24 has an outer wall 24a which is concentric to
the axis of rotation R1, R2. The housing 26 is provided with a wall 26a
which is concentric to the axis of rotation R1, R2. The diameter of the
rotational head 24 is larger than that of the housing 26 so that a
shoulder 28 is formed between the outer wall 24a and the wall 26a with
which the rotational unit 22 partially engages its associated recess 16,
see FIG. 1a.

[0043] The dimensions of the housing 26 are adapted to the respective
associated portions of the recesses 16. To ensure the non-rotatable
connection of the housing 26 and the rotor head 12, a groove is formed in
the housing 26 parallel to the axis of rotation R1, R2 and a projection
is provided on the rotor head 12, which projection is associated with the
groove. For the sake of clarity, the groove and the projection are not
shown in the figures. Moreover, the arrangement of the groove and the
projection may also be reversed. Furthermore, it is also conceivable to
choose a polygonal design instead of the cylindrical design of the
housing 26 so as to ensure that the housing is mounted in the rotor head
in a non-rotatable manner.

[0044] According to FIG. 1a, the rotational head 24 is furthermore closed
on the side remote from the housing 26 by a closure cap 30 which is
concentrically arranged relative to the axis of rotation R1, R2. A
closure knob 32 is likewise concentrically arranged on the closure cap
30, which knob 32 serves as a handle to unlock the closure cap 30 by a
rotary movement and remove it, and/or to put the closure cap 30 on and
lock it in place by a rotary movement against the unlocking direction.

[0045] A circumferential projection 34 is provided on the upper wall 24a
adjacent to the shoulder 28, see FIG. 2 for example, which projection 34
securely mounts a gearing 36, which is non-rotatably connected to the
wall 24a, in a concentric alignment relative to the axis of rotation R1,
R2. For transmitting the rotary movement of the rotational heads 24 about
the axes of rotation R1, R2 of the rotational units 22, a gear is
provided below the rotor head 12 for each rotational head 24, which gear
is not shown in the figures for the sake of clarity. This gear 24 is in
engagement with the gearing 36 on the one hand and with a central gear 40
which is non-rotatably connected to a motor housing not shown in the
figures opposite the rotatable rotor head 12, for example by a screw
connection. Such a transmission of rotary movements is well known and
described in the prior art, so that no further explanations are required
here.

[0046] The ratio of the main rotation (rotation of the rotor 10) to the
reverse rotation (rotation of the rotational head 24) is given by the
transmission ratio between the gear wheel (not shown) and the central
gear 40. With the rotor head 12 removed, the gear (not shown) and the
central gear 40 can be easily replaced. Therefore the speed ratio can be
changed easily, by adapting the diameters of the gear (not shown) and the
central gear 40.

[0047] The side of the housing 26 which is remote from the rotational head
24 has cooling ribs 42. The cooling ribs 42 are aligned perpendicular to
the direction of rotation of the rotor head 12.

[0048] FIG. 2 is a perspective view of an inventive embodiment of a
rotational head 24 without the gearing 36. Evenly spaced recesses 34a are
arranged along the entire periphery of the projection 34 through which
screws 36a extend which are provided on the underside of the gearing 36,
as seen in FIG. 1a, and which engage in associated threaded bores in the
gearing 36. The screws 36a extending through the recesses 34a securely
mount the gearing 36 on the wall 24a and in the rotational head 24 and in
particular ensure that the gearing is non-rotatably mounted relative to
the rotational head 24.

[0049] Within the wall 24b, walls 44 are mounted on a base plate 24b,
which walls 44 are adapted to securely mount an adapter 50 shown in FIG.
3 for material to be centrifuged. The walls 44 define an inner profile
which is matched to the outer profile of the adapter 50 of FIG. 3, which
adapter 50 has a cross-shaped base area of two superposed rectangles
which are concentrically rotated orthogonally to each other. The walls 44
are partially connected to each other for improved stability. Four walls
44, of which two each are disposed opposite each other as a pair, each
have an outer profile 44a formed thereon which is rounded in such a
manner that it is concentric with the wall 24a. The wall 24a has four
equally spaced bores 24c adjacent its upper edge, which bores 24c are
adapted to lock the closure cap 30 that has corresponding projections.

[0050] FIG. 3 is a perspective view of the aforementioned adapter 50 for
material to be centrifuged. On the periphery of the aforementioned
cross-shaped base area, the adapter 50 has vertically disposed integral
outer walls 52. Within the outer walls 52, five rectangular recesses 56
are provided which are delimited from each other by partition walls 54,
with the vertical extension of the recesses 56 corresponding to the
vertical extension of the wall 24a of the rotational head 24. The
recesses 56 are used to receive the sample container receptacles not
shown in the figures and are adapted to the shape of the sample container
receptacles.

[0051] Adjacent to the free upper edges of the outer walls 52 of the
adapter 50, a bearing surface 58 is disposed perpendicularly on the outer
walls 52, which surface 58, in the inserted state of the adapter 50, will
rest on the free upper edges of the walls 44. The bearing surface 58 has
an outer contour 60 which is substantially concentric with the wall 24a
of the rotational head 24 and which has four bulges 62 which are equally
spaced from one another over the periphery. The bulges 62 facilitate
handling of the adapter 50 during insertion into and removal from the
rotational head 24.

[0052] FIG. 4 is an exploded view of the rotational unit 22 comprising the
rotational head 24 and the housing 26 with a bearing unit 70 integrated
in the housing 26, with a drive shaft not shown for reasons of clarity
extending concentrically through said bearing unit 70.

[0053] Starting from the housing 26, disposed along the axis of rotation
R1, R2 are a clamping nut 72 for biasing the bearing unit 70, two
single-row angular contact ball bearings 74a and 74b, an outer washer 76
located between the angular ball bearings 74a and 74b, as well as an
inner washer 78 and a cover disk 80. All of the above elements of the
bearing unit 70 have concentric bores, through which the bearing shaft 25
of the rotational head 24 extends in a play-free manner.

[0054] On the cover disk 80, eight recesses 82 are provided at equal
intervals and adjacent to the outer periphery. On the side associated
with the rotational head 24, the housing 26 has a flange 84 which in turn
has eight recesses 86 arranged at regular intervals that are associated
with the recesses 82.

[0055] FIG. 5a is a bottom view of the rotational unit 22. A cylinder
screw 88 each engages the recesses 82 of the cover disk 80 and extends
through the associated recesses 86 of the flange 84. Five recesses 82a
each and five recesses 86a associated with the recesses 82a are provided.
The cylinder screws 88 provide a screw connection of the housing 26 and
the cover disk 80 in such a way that they, together with the bearing
shaft 25 of FIG. 2, delimit a bearing space (64) which is encapsulated
toward the outside in a lubricant-tight manner (see FIG. 5b).

[0056] It is well known how to fit angular contact ball bearings in pairs
and how to bias them, so that further explanations are unnecessary here.

[0057] FIG. 5b is a view of a cross-section of the mounted rotational unit
22 shown in FIGS. 4 and 5a taken along a line C-C depicted in FIG. 5a. A
lubricant refill valve having a valve line 92 is provided on the wall 26a
between the bottom plate 24b and the angular contact ball bearings 74b.
If necessary, this lubricant refill valve can be used to refill lubricant
into the bearing space 64 which is encapsulated from the outside in a
lubricant-tight manner. A lubricant level indicator 90 arranged on the
wall 26a outside the housing 26 is used for inspecting the lubricant
level.